Progressive fork springs

[Kurt]

Have had my 76 wing bout a month and do love it.. I'm just a little surprised that the front suspension dosen't soak up little bumps better than it does given weight of bike. I just wondered of anyone has tried aftermarket progressive fork springs and if there is a noticeable benefit. Guidance appreciated! thanks Kurt (ps I have changed fork oil to AFT)

[ericheath]

Yes and most who change cannot believe the difference. Much improved.

[Whiskerfish]

see for me it was the opposite. I have had progressives and replaced them with stock. But I usually do add something to the top of the stock springs like a clutch spring or a valve spring. Been a long time but as I recall I found the progressives harsh especially on my dresser.

[RB]

First try heavier wt. oil, if still too soft add a spacer..stack of washers or piece of pipe 1/2 to 1' usually works. You can also modifiy to add air..but that's more involved.

[jdvorchak]

Measure the sag and compare it to the spec in the FSM. I went with progressives when I discovered the stock springs were worn out. They are a harsher ride but no more bottoming out which is what I suspect you are feeling. And no need to put air in them anymore.

Heavier fork oil will stiffen up the ride but oil doesn't hold the bike up. The springs do.

[Sagebrush]

It been a positive world of difference on every bike that I switched the front fork springs to progressive. I don't know what happened to Whiskerfish but my personal experience and those of the folks that I ride with that switched all raved about the better ride.

[rcmatt007]

I find they are stiff.... but I am not big. Your bike may already have progressives in it

[calif wingnut]

In a 77 Rider magazine as I recall, they did a suspension article on the gl1000 testing all front/rear end aftermarket kits available at the time. Their bottom line was the rear was fixable while the front was hopeless, suffering from excessive stiction/tube flex/poor dampening and poor quality control in the bottom fork leg machining etc, etc=a jack hammer on wheels.

I have the mag here but have to find it.

[robbie202]

would a brace help?

[rcmatt007]

a brace helps with the flexion. But Calif is right, the 1000 front end is not a strong point. I think they actually used the one off a 750. The later 1100s and the 1200s are far superior

[Old Fogey]

The 750s have even thinner tubes, 34mm if my memory serves me.
I have a spacer on the springs, a brace and 7wt oil; they are still crap.

[rcmatt007]

It is important to put them into the context of the time. You simply cannot compare a bike of that era, except to what else was available at that time.... having sad that, OF is right, the front ends are crap

[calif wingnut]

First generation CB750 forks are 35mm. The 1100/1200/1500/1800 all use top and bottom Du teflon tube bushings which work fine.

[BlueThunder]

Yes, but aren't the '75-'77 have 37mm?

[Kurt]

Ok.. so I decided to give the progressive springs a try.. noticed that stock springs have almost no preload.. maybe 1/4 in. at most. So changed the fluid (ATF) and installed progressive springs (bout 3/4 in preload) close winds down. Manual said makes no difference but may have less spring noise that way. Did not see much of any difference from the stock springs. But remember reading somewhere the close winds should be at top and I had some 10 wt semi-synthictc quality fork oil left from my Bonneville.. drained forks, reversed springs and used 10 wt oil.. I also put a thin washer size of spring greased with silicone grease between plug and spring. (just seems like most bikes iv had used a washer between plug and spring) I would say I see a 50% improvement. Don't notice the little bumps near as much big ones are a little smoother too.. may be a bit more nose dive under heavy braking but will take the trade off for ride improvement. FYI..